I'm not sure where in the Northeast you live, but I'm in Baltimore, a
little south of you, no doubt, and found when exploring the same
question that without heating, cooling and powered ventilation, I would
only be able to use a greenhouse about four or five months a year,
Spring and late Summer-early Fall. The rest of the time it's just too
hot or too cold. Realizing that, I invested instead in an HID light,
HPS in the Fall and Winter, MH conversion bulb in the Spring and
Summer. Seems to work well, no insect problems, and while not as much
fun as a greenhouse might be, actually more growing room than I would
have had in a reasonably priced GH. Just some thoughts.

CP